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New Fuel line with Wipac filter now in place. Only a little blood lost! At least I got to drain the tank & will put the fuel through a filter before putting it back. I have found a few of layers of J cloth in the funnel is a good filter, probably works as a Covid19 face mask too !
I think I will have to bite the bullet & take the switchboard apart and give it a good clean....I have done them before, just try not to break off any crumbly Bakelite this time. At least all the wires are clearly & correctly labelled.
If that doesn't work I suppose the dynamo will have to come off and be "Examined" - before that though... with engine running what should I expect as voltage at the terminals? Should I disconnect the wires when testing? I have seen 7-8 volts at the battery in the past, so the fault is just lurking, waiting to be found !
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Location: On a hill in Wiltshire
Maybe you could borrow a good dynamo, which would show you where the fault lies.
If your dynamo is looking "cooked" maybe it has an intermittent fault which is why it is so difficult to diagnose.
One further thing: are you as sure as you can be about the earth connections everywhere?
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Refreshing the switchboard at the moment, I will put an earth from motor onto the frame....the car has home made flexible engine mounts from the 60s, so that is a good idea!
D
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Location: On a hill in Wiltshire
I would rig up temporary connections if they are not already there:
I assume there is a battery lead directly to a place on the crankcase - usually a gearbox stud.
I would take a wire from here to the earth on the control box, one to a dynamo mounting bolt.
Those are the earths involved in the charging circuit - the chassis or body shouldn't come into it.
For the rest of the electrical system I try to run a separate earth wire from every component back to a commom earth point - I have one under the rear seat and one by the control box, and thes points are in turn connected the the main battery earth.
Whilst the original earths to body or chassis are still there, I don't rely on them. I think the only thing without a separate earth is the horn.
Cheers
Simon
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15-05-2020, 08:09 AM
(This post was last modified: 15-05-2020, 08:14 AM by David.H.)
Main battery negative earth strap goes to the body using the original point under the passenger seat.
I always used a single earth point for accessories on my rally cars, this used with relays for anything with a switch meant that electrical problems were happily non existent, even on 10000 mile marathons to Australia!
I have fitted relays for the dip system as the original switch on the column is tiny!
I will run a reasonably heavy lead to a gearbox stud.....with the isolater switch it is getting a bit crowded round the terminal post
In addition a strap from the block to chassis, although the system does seem to rely on the steel body as it's ground.The control box earth is a short lead to the bulkhead earth point.
One change at a time so I can see if anything works!
Perhaps we should treat a Seven like a fibreglass bodied car! I had a TVR Tamsin once and every wire on the car was black....Originally they had coloured tags by the terminals, but by the time I had it they had all gone beige! Mind you I never had a single electrical problem. OK the headlights went out occasionally. .......!
Thanks for your helpful comments.
David
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Location: Far West of New Zealand
'A Gentleman Does Not Motor About After Dark'
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Back to the Seven problem!
The Switchboard has been taken apart & reassembled and looks and feels good!
All the wires are in (I think) the right places.
Ignition on...Summer Charge....warning lamp on. So far so good.
Start up...Warning lamp dims & almost goes out.
Ammeter not reading positive. Increased negative when lights switched on.
What happens if I move to Summer Charge?...Warning lamp becomes VERY bright...Promptly switch back to Summer!
I had connected an additional earth from engine to body.
Any ideas?
Joined: Aug 2017 Posts: 772 Threads: 26
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Location: On a hill in Wiltshire
The difference between Summer and Winter charge: in "Winter" switch position, the two dynamo terminals are connected together, so the Field (smaller wire) gets lots of supply and so makes more electricity.
In "Summer", the supply to the Field goes through the field resistance which lowers the juice to the field and the dynamo makes less electricity and so isn't working too hard during the Summer.
This resistance, as standard, is a coil of rusty wire about 3/8" diameter and about 2 1/2" long, it usually lives under the control box, or sometimes in its own box on the dynamo.
It is also often broken. If broken and the switching is working, you get full charge on "Winter" and none on "Summer"
I have read back, the field resistance has only been mentioned once. And reading back reminded me that you had a problem with the ignition light - which has its own resistance in the form of a coil of thin wire wrapped around the holder. Which I am not sure you got to the bottom of whether the assembly was the correct spec, or connected correctly.
Did you get the cut out to close when revving?
Have you checked the state of the field resistance and its connections?
Are you sure the warning light is correct in spec and connections - it almost sounds as if the field current is going through it - it isn't clear from your last what happens when, I think you have written "Summer" twice, when one of them should be "Winter".
For a simple system, it ties us all up in knots - don't get down, it will get sorted.
Easy solution to get mobile is just run on the battery - see a previous thread a week or two ago - and have another go at it later. Gives you time to borrow cut-out, dynamo, switch, ignition light, as required, to swap over and nail the problem.
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Location: Deepest Frogland 30960
Car type: 1933 RP Standard Saloon
David, if it's any help ( and I appreciate my RP has a slightly different set-up. On starting the engine with summer setting selected, the ignition lamp glows until I raise engine revs to a certain level whereby the dynamo output is high enough to cause the voltage regulator to close and the ign lamp goes out. On winter setting the dynamo output is higher so it takes less revs to generate the same output. However until the regulator trips the ign lamp does get brighter until the cut- off occurs. I use a 12v bulb. Dynamo output is set to give max 8amps on winter. Hope that helps.
